Shaatnez שעטנז
The ban on wearing cloth in which wool is mixed with linen—a law for which the Torah gives no reason.
"You shall not wear shaatnez—wool and linen together." The ban concerns clothing only, and these two threads only; wool with silk or linen with cotton is permitted. The word "shaatnez" puzzles even the language: the sages read it as an abbreviation of three words for spinning, weaving and twisting.
It is the model of a "chok", a law without a stated reason; the Midrash ties it to the offerings of Cain and Abel—linen from the farmer, wool from the shepherd. Today garments are examined in shaatnez laboratories under a microscope, because a linen thread in a wool suit cannot be seen by eye. The laws are in tractate Kilayim.
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Sources
Tanakh
- Deuteronomy 22:11 — «you shall not wear shaatnez»
- Mishnah Kilayim 9:8 — spun, woven and twisted
Basis: stated in the Tanakh.